Automotive airbags are commonly installed to protect both the driver and the front seat passenger from injury in the event of a head-on collision. The term "airbag" is something of a misnomer because typically the bag is filled with a rapidly evolving gas produced by an igniter. The bag is designed to inflate in no more than approximately 15 milliseconds. In its uninflated and folded condition it is mounted within a housing having a cover which is designed to tear along predetermined lines to provide an opening for the escape of the airbag.
In view of the explosive nature of the airbag inflation, one of the major problems with prior art installations has been the tendency of the airbag cover to break into pieces. The pieces thereupon become projectiles capable of striking the occupants.
Airbag covers customarily are formed of materials such as thermoplastics which are somewhat resilient and have weakened or thinned regions forming tear lines. The tear lines are designed to rupture and form one or more hinged doors which permit the expanding airbag to escape. Ideally the shearing stress which bursts the tear lines is dissipated within sufficient time and distance to allow the formation of hinges which permit the doors to open but retain them in place on the cover. It would also be desirable for the doors to swing open through an arc exceeding 180.degree. in order for them to be positioned well clear of the expanding airbag. Finally, it would be desirable to achieve these objectives while employing a one piece molded cover without the need for inserts or hardware elements.